I-365, a solvent and precursor for other chemicals, is a byproduct formed during the manufacture of I-141b, a replacement for trichlorofluoromethane as a blowing agent. Since commercial specifications for I-141b normally call for 99.5% purity, a method for I-365 removal is needed, desirably to levels below 0.5%. Separation by conventional distillation means is extremely difficult, however, since I-365 and I-141b form an azeotrope.
While liquid-liquid extraction has been reported in U.S. Pat. No. 4,031,148 for separating chlorinated hydrocarbons by the use of water-miscible solvents and 0-50% water, applicant is not aware of literature which discloses liquid-liquid extraction for separating HFC's (hydrofluorocarbons) such as I-365 from HCFC's (hydrochlorofluorocarbons) such as I-141b. Also, as noted in column 1, lines 53-56 of said U.S. Pat. No. 4,031,148, and as demonstrated by copending application Ser. No. 751,023, filed on even date herewith, it is impossible to foresee which extraction agents will enable the separation of any two substances.